Study of Infectivity Ability of Local Isolates of Leishmania Tropica and Determination the Degree Of Susceptibility to Amphotericin B In Vitro

Abstract

Leishmania tropica is considered the main species that causes cutaneous leishmaniasis (CL) in all Syrian governorates. Current treatments are based on pentavalent antimony compounds which are used to treat this disease alone or in combination with second-line drugs such as amphotericin B. Recently, therapeutic results of these drugs have become less than ideal, that reflects the presence of different degrees of drug sensitivity and various phenotypes. Therefore, it is necessary to evaluate the local Leishmania isolates in terms of infectious ability and the degree of sensitivity, specifically to amphotericin B, in case it will be used more widely in future.

 Based on previous facts, this study aimed to characterize these local isolates

of L. tropica in terms of their infectious ability to human macrophages in vitro and evaluate the susceptibility of these isolates to amphotericin B.

This research was done by calculating the Half-maximal inhibitory concentration (IC50) for four local isolates (L1 – L4) after treatment with (AmB) for 24 hours, and monocytes were isolated from human peripheral blood and differentiation into macrophages, then infected by promastigotes of Leishmania Parasites for determination the percentage of infected macrophages and the parasite burden.

The values of IC50 revealed different degrees of susceptibility to (AmB) between four isolates. in addition, our results represented significant differences between L3 isolate and others in terms of infectivity ability and parasite burden. Finally, it is worth noting that the third isolate (L3) was the most infectious to macrophages and the lowest resistant to amphotericin B at the same time.